Looking through the datalogs from our ZM TB testing i noticed some one or two knock counts on a few runs. It was 40'* weather, rainy, and I'm running straight 87 with 10% ethanol.

KR went up to 4 degrees after the 2nd count in one of my WOT runs. The 2nd Knock count occurred around 3500RPM, and killed timing until the end of the WOT run. I had a stored Code 042.

A few possibilities, perhaps my 147k cat, some hot spots in Cyl heads, etc.... Everything seems bolted down good in the engine bay, but i haven't checked in a while. Plugs are 1.5 years old IIRC, NGK TR-55 1 range colder.

EDIT:Fueling seemed on the rich side, O2 has about 40k on it, almost 4 years old.

Your PCM needs time to learn the new flow. Keep in mind that the amount of flow you had at any given angle based on TPS voltage BEFORE is now flowing more.